Shelf



FIG. 1 is a top, front, left perspective view of a shelf showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof; and,

FIG. 8 is a bottom, front, left perspective view thereof.

The broken lines immediately adjacent to the shaded area define the bounds of the claimed design and form no part thereof. The broken lines depicting the remainder of the shelf show features that form no part of the claimed design. The appearance of any portion of the article between the zig-zag broken lines and brackets forms no part of the claimed design. 

CLAIM The ornamental design for a shelf, as shown and described. 